Note: This monograph does not include wasabi (Wasabia japonica), for which horseradish is a common substitute.

Note: The U.S. Food and Drug Administration (FDA) defines horseradish as the root of Armoracia lapathifolia Gilib. This monograph uses the more common scientific name Armoracia rusticana, which is used by the U.S. Department of Agriculture (USDA).

Horseradish (Armoracia rusticana) is a hardy perennial plant of the Brassicaceae family, which includes mustard and cabbage. Large doses by mouth can cause gastrointestinal upset, bloody vomiting, diarrhea, and irritation of mucous membranes and the urinary tract. Horseradish may also provoke allergic reactions.

Although horseradish may be irritating, it is frequently used as a condiment or spice, especially for beef, sausages, and fish. The U.S. Food and Drug Administration (FDA) has approved horseradish (Armoracia lapathifolia Gilib.) as Generally Recognized as Safe (GRAS) as a seasoning, spice, and flavoring (the FDA currently accepts Armoracia lapathifolia as the binomial name for horseradish, although Armoracia rusticana is more commonly used and is the preferred name by the U.S. Department of Agriculture).

Traditionally, horseradish has been used for pain, rheumatism, and cancer. It has also been studied for bronchitis, sinusitis, and urinary tract infections, but additional study is needed before making firm recommendations.

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

GRADE *

Horseradish may have antibiotic activity, and has been used in combination with other herbs to treat bronchitis. However, additional studies are needed that use horseradish as a single therapy before a strong recommendation can be made.

C

Horseradish may have antibiotic activity, and has been used in combination with other herbs to treat sinusitis. However, additional studies are needed that use horseradish as a single therapy before a strong recommendation can be made.

C

Horseradish may have antibiotic activity, and has been used in combination with other herbs to treat urinary tract infections. However, additional studies are needed that use horseradish as a single therapy before a strong recommendation can be made.

C

* Key to grades

A: Strong scientific evidence for this useB: Good scientific evidence for this useC: Unclear scientific evidence for this useD: Fair scientific evidence for this use (it may not work)F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

There is no proven safe or effective medicinal dose of horseradish in adults.

Children (under 18 years old)

There is no proven safe or effective medicinal dose of horseradish in children.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in individuals with a known allergy or hypersensitivity to horseradish (Armoracia rusticana), its constituents, or members of the Brassicaceae family. Large doses taken by mouth may provoke allergic reactions.

Side Effects and Warnings

Horseradish is likely safe when the root is used in food amounts. The U.S. Food and Drug Administration (FDA) has approved horseradish as Generally Recognized as Safe (GRAS) as a seasoning, spice, and flavoring.

Use cautiously in patients with low blood pressure or taking antihypertensives, as horseradish in medicinal amounts may lower blood pressure.

Use cautiously in patients taking anti-inflammatory agents, as horseradish may inhibit COX-1 enzymes.

Use cautiously in patients undergoing treatment for cancer, as horseradish and horseradish combined with indole-3-acetic acid may have antineoplastic (anticancer) activity.

Use cautiously in patients with thyroid disorders or taking thyroid hormones, as medicinal amounts of horseradish may interact with thyroid medications.

Avoid medicinal amounts of horseradish in patients who are pregnant or breastfeeding, as glucosinolates from horseradish are considered a toxin that can be excreted through breast milk and may pose a toxicity hazard.

Use cautiously in patients with kidney disorders, kidney inflammation, gastrointestinal conditions, or ulcers, as horseradish may have strong diuretic (increased urination) effects.

Use cautiously in patients with stomach ulcers.

Pregnancy and Breastfeeding

Avoid if pregnant or breastfeeding. Horseradish has been used to induce abortion. Certain chemicals, such as glucosinolates, from horseradish are considered toxins that can be excreted through breast milk and may pose a toxicity hazard.

Horseradish may have antibiotic activity. Use cautiously with antibiotics, due to additive effects.

Horseradish may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Horseradish in medicinal amounts may have hypotensive (blood pressure-lowering) activity. Use cautiously with blood pressure medications.

Horseradish may inhibit COX-1 enzymes. Use cautiously with anti-inflammatory agents, due to possible additive effects.

Horseradish may have antineoplastic activity. Use cautiously with anticancer medications, due to possible additive effects.

Horseradish root may have oxidative activity; use cautiously with other antioxidants, due to possible additive effects.

Medicinal amounts of horseradish may interact with thyroid medications.

Horseradish may have strong diuretic (increased urination) effects.

Medicinal amounts of horseradish may interact with thyroid medications; use cautiously.

Interactions with Herbs and Dietary Supplements

Horseradish may have antibiotic activity. Use cautiously with antibacterial herbs and supplements, due to possible additive effects.

Horseradish may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto.

Horseradish may inhibit COX-1 enzymes. Use cautiously with anti-inflammatory herbs and supplements.

Horseradish may have antineoplastic activity. Use cautiously with anticancer herbs or supplements.

Horseradish root may have oxidative activity. Use cautiously with herbs or supplements with antioxidant activity.

Horseradish may have strong diuretic effects. Horseradish may also have beneficial effects when taken with the phytohormone, indole-3-acetic acid, although human evidence is lacking in this area.

Horseradish in medicinal amounts may have hypotensive (blood pressure-lowering) activity; use cautiously with blood pressure medications.

Horseradish contains tannins and vitamin C, which may have additive effects when taken with other tannin-containing herbs or vitamin C supplements.

Medicinal amounts of horseradish may interact with thyroid medications; use cautiously.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.